Effects of Radiation upon Electronics
As is known in the art, the outer space environment contains a number of high energy protons, electrons, and heavy ions. Some of these protons, electrons, and particles are trapped in the Van Allen belt that surrounds the Earth. Similarly, high energy particles are known to be located near objects in outer and deep space, such as planets, stars, moons, and other naturally occurring satellites. As high energy particles from these various sources strike materials, the high energy particles cause direct ionization of the struck material. Unfortunately, the struck material includes man-made orbiting satellites, deep space probes, space stations, shuttles, other space craft and the like, collectively referred to herein as simply “satellites.” These satellites are further known to contain a multitude of electronic devices, circuits, and on board computer and/or telecommunications equipment.
A source of incident radiation in terrestrial environments is high-energy particles generated from the interaction of cosmic rays with the atmosphere. These particles are not always generated by direct ionization but are typically indirectly generated as by-products of the high energy particles mentioned above. Also known in the art, the high energy particles can further have silicon ionizing effects. Moreover, decay of radioactive impurities in silicon and alpha particles generated from packaging are yet more sources of silicon ionization.
Accordingly, the semiconductor components of electronic circuitry are often exposed to ionized or charged particles. As mentioned above, the energy level of some charged particles is high. If the energy level of a charged particle is high enough, the particle can penetrate through to the packaging and shielding of a typical electronic circuit, to strike the components of the circuit, and/or to cause direct ionization of the semiconductor components of the circuit. This phenomenon is known in the literature as a Single Event Upset (SEU) of the electronic circuit. Single Event Upset has been studied by the research community. For example, see T. Ma and P. Dressendorfer, IONIZING RADIATION EFFECTS IN MOS DEVICES & CIRCUITS CH. 9, New York, N.Y., John Wiley & Sons, 1989. See also, J. Gambles and G. Maki, Radiation Effects and Hardening Techniques for Spacecraft System Microelectronics, IAF World Space Congress, Reference IAC-02-I.05.08. October 2002, which is incorporated herein by reference.
Further, if a high energy charged particle passes through a semiconductor diffusion region of an electronic device, such as a transistor, particularly at a susceptible node within the electronic circuit, then the particle can undesirably alter the contents of data stored within the electronic circuit. A particularly susceptible node within electronic circuits is a logic cell. The logic cell includes, for example, a metal oxide semiconductor (MOS) logic cell. Logic cells use data in the form of binary logic (as a 1 or a 0).